You do not always need a colostomy for the treatment of colon cancer. In fact this has become less and less common as surgical methods have improved over the years. Surgery is the most common treatment for colon cancer. If the cancer is limited to a polyp, the patient can undergo a polypectomy (removal of the polyp), or a local excision, where a small amount of surrounding tissue is also removed. If the tumor invades the bowel wall or surrounding tissues, the patient will require a partial resection of the bowel (removal of the cancer and a portion of the bowel) and removal of local lymph nodes to determine if the cancer has spread into them. After the tumor is removed, the two ends of the remaining colon are reconnected, allowing normal bowel function. In some situations, it may not be possible to reconnect the colon, and a colostomy is necessary. A colostomy is when the surgeon passes the end of the colon through the abdominal wall and connects it to the outside of the abdomen, creating an outlet for stool to pass through. Equipment, known as "appliances" are attached to the abdominal wall to collect the stool.

There are times when a colostomy is necessary temporarily. After the patient has had some treatment with chemotherapy and radiation, the surgeon may be able to reverse the colostomy by reconnecting the bowel ends. Whether or not a patient has a temporary, permanent, or no colostomy at all is determined by the size and location of the tumor, which the surgeon evaluates by CT scan and during surgery.